Generally, a shock absorber for generating a damping force and a suspension spring for biasing the shock absorber in an extending direction are provided in parallel between a vehicle body and a wheel in a vehicle to suppress the transmission of a shock caused by road surface unevenness to the vehicle body by absorbing the shock caused by the road surface unevenness by the suspension spring and suppressing extending and contracting motions of the suspension spring associated with shock absorption by the shock absorber.
Further, if the vehicle is loaded with a large amount of freight and/or many passengers, compression amounts of the suspension spring and the shock absorber may become large and a vehicle height may become too low. On the contrary, if the vehicle is loaded with a small amount of freight and/or a few passengers, the compression amounts of the suspension spring and the shock absorber may become small and the vehicle height may become too high. Accordingly, a vehicle height adjusting device for adjusting the vehicle height is installed in a vehicle in some cases.
For example, a vehicle height adjusting device disclosed in JP2010-149550A includes a movable spring bearing mounted on the outer periphery of an outer tube of a shock absorber and configured to support one side end of a suspension spring for biasing the shock absorber in an extending direction, and a driving mechanism configured to drive the movable spring bearing in an axial direction of the shock absorber.
Accordingly, if a vehicle height becomes too low, the driving mechanism is actuated to drive the movable spring bearing toward the suspension spring, whereby the vehicle height can be increased by extending the shock absorber. Further, if the vehicle height becomes too high, the driving mechanism is actuated to drive the movable spring bearing toward a side opposite to the suspension spring, whereby the vehicle height can be decreased by compressing the shock absorber.